The Never Ending Endler debate; A species or not?
© Alan S. Bias
Permission granted
for nonprofit reproduction or duplication of photos and text with proper credit
for learning purposes only.
I
have just finished reading “Klee (2013), Endler’s Guppy: A Species Or Not A Species?” for the
third, or is it fourth time? This in
conjunction with quick re-reads of several publications by Breden, Poeser and
Schories. While Klee does not come forth
in outright “support” of Schories (2009) & Poeser (2005) in proclaiming P. wingei a distinct species, it seems he
is leaning in that direction.
The
author does a well in laying out the processes used in naming a new
species. Even more so in explaining the
various scientific schools of thought, technology and terminology quoted for reader
understanding. In the end he wisely shy’s
away from proclaiming P. wingei a
distinct species citing lack of current consensus among scientists
themselves. What other option did he
have?
It
seems modern technology will further create schism between the divergent
schools of thought found within the scientific community for some time to
come. Traditional criteria for
classification of variant populations as new species within a genus are being
ignored in favor of micro classifications under the auspices of cryptic species
complex. In the past it was often
considered paramount speciation be set at the largest group capable of viable
reproduction. Localized differences
identified as sub-species. Should
science allow this to fall by the wayside?
Klee
relies heavily on Schories (2009), who in turn is supportive of Poeser
(2005). Schories does well in making
visible morphological and mitochondrial (mtDNA) distinction between variant
populations of P. reticulata caroni
and P. reticulata obscura, in her
effort at describing the latter as a distinct species. Supportive of Poeser’s classification of P. reticulata wingei as a distinct species adds
further preponderance of weight. Poeser
on the other hand relies to a lesser degree on mtDNA and favors morphological
evidence in proclaiming P. reticulata wingei
as a distinct species. Schories in
turn relies on mtDNA distinction in separating wingei as a distinct tree in
phylogeny. In her comparison between
other related species a similar range of genetic difference is revealed in
support of mtDNA based evidence of speciation.
Likely
the most problematic criteria being used to define new species within a phylogenic
tree is mitochondrial DNA (mtDNA). While
there is little doubt that the use of molecular genetics to create phylogenetic
trees is of long-term value in showing relationship, can mtDNA alone be used to
define a species and signify cryptic speciation? The primary argument most seen being mutation
within maternally passed mtDNA is less frequent than DNA and is confined for the most part within
itself through self-replication. Thus, mtDNA
is more static in nature as compared to DNA, and less subject to “pollutants”
from various sources.
Phylogenetic
result in itself is often a very “assumptive” process. When results are postulated solely from
single sided mtDNA evidence, it would seem a large part of the story is being
ignored. Many ancient native cultures around the
world are based on maternal lineage. Domestic
livestock breeding is often tracked within maternal family groups in a breed. While concentrating mtDNA, neither situation
results in rash proclamation of new species, only sub-populations and breeds. Maternal lineages are noted for directing speciation in
the wild through sexual selection and preference. Without morphological differences and a loss of
viability between populations stemming from a common ancestral lineage, I have a hard time viewing maternal lineages as
anything greater than family groups and sub-populations found within the greater
population.
In
the end this leaves breeders with the same dilemma Klee presents in
summary; Science cannot reach
consensus on P. reticulate wingei as a variant population or species. So, why should we as breeders be overly worried about speciation status between variant guppy populations
in the process of incipient speciation? Personally, I see no reason. As breeders our efforts should be focused on identification and
retention of phenotypic traits from any of the three Guppy variants for incorporation into strains of Domestic
Guppies.
REFERENCES
Alexander, Heather J. and Felix
Breden, “Sexual isolation and extreme morphological divergence in the Cumana
guppy: a possible case of incipient speciation,” Journal of
Evo-lutionaryBiology, 17, pp. 1238-54, 2004.
Klee, Albert J., (2013), Endler’s
Guppy: A Species Or Not A Species? http://www.igees.org/ENDLERS_GUPPY_A_SPECIES_OR_NOT_A_SPECIES,
last checked 2.6.2014.
Poeser, F.N., M. Kempkes, and I.J.H. Isbrücker, “Descr iption of
Poecilia (Acanthophacelus) wingei n. sp. from the Paría Peninsula, Venezuela,
including notes on Acanthophacelus Eigenmann, 1907 and other subgenera of
Poecilia Bloch and Schneider,1808 (Teleostei, Cyprinodontiformes,
Poecili-idae).Contributions to Zoology74: 97–115,2005.
Schories, Susanne, Manfred K. Meyer & Manfred Schartl , “Descr
iption of Poecilia (Acanthophacelus) obscuran. sp., (Teleostei:Poeciliidae), a
new guppy species from western Trinidad, with remarks on P. wingei and the
status of the “Endler’s guppy,”Zootaxa,2266: 35–50, 2009.
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Consider asking a knowledgeable breeder for help
in identifying a unique trait you just observed
in your strain before culling. Never know,
it might just be the newest mutation in the world of Guppies.
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